SuperNova on 18 September 2017
If Switch coninues to deliver on it's promise and the momentum keeps up, I'm thinking late 2021 to early 2022.
The 3DS is still getting good support, but it'll probably start to taper off in 2018. It will probably reach 75m or just short of it, the current Switch sales trends give reason to be optimistic about it's life time, so I'm thinking it will beat the 3ds within 5 years.
